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<head><title>HTTP/1.1: Access Authentication</title></head>
<body><address>part of <a rev='Section' href='rfc2616.html'>Hypertext Transfer Protocol -- HTTP/1.1</a><br />
RFC 2616 Fielding, et al.</address>
<h2><a id='sec11'>11</a> Access Authentication</h2>
<p>
   HTTP provides several OPTIONAL challenge-response authentication
   mechanisms which can be used by a server to challenge a client
   request and by a client to provide authentication information. The
   general framework for access authentication, and the specification of
   "basic" and "digest" authentication, are specified in "HTTP
   Authentication: Basic and Digest Access Authentication" <a rel='bibref' href='rfc2616-sec17.html#bib43'>[43]</a>. This
   specification adopts the definitions of "challenge" and "credentials"
   from that specification.
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